Abstract : Perceived Noise Level (PNdB), a technique for measuring aircraft noise, is calculated from measured noise levels and correlates well with subjective judgments in terms of annoyance and noisiness. The discussion considers the effects of physical laws and evironmental factors which attenuate, both predictably and variably, the sound pressures reaching the ground. The effects of psychological factors which influence subjective judgments are also discussed. It is suggested the effect of these factors is such that Perceived Noise Level is of useable precision and additional refinement would be superfluous. The procedure for predicting community response to airport operations using Composite Noise Ratings is discussed. Actual measurement of aircraft noise is not required. Noise contours of aircraft operations exist, and these are used in conjunction with airport operations data in a simplified procedure to derive a prediction of community response. In an effort to improve the sensitivity of the prediction process to local conditions, a separate study was made of the decision-making process on the municipal level. A definitive pattern could not be discerned and it was concluded the existing predictive procedure cannot be made more sensitive to communtiy reaction at this time. (Author)